Precipitation such as rain, snow, sleet, hail and the like can be collected in reservoirs or tanks and then can be treated and used as mains water. Drainage systems can be set up, separate from sewage systems, to collect such water from precipitation. Water from precipitation requires less treatment before it can be used as mains water than is required by water from sewage systems and it is therefore desirable to collect water from precipitation separately from water from sewage systems. Water from precipitation can be collected separately from water from sewage systems by directing water that has been collected in guttering of buildings down drainpipes and piping it to storage tanks or reservoirs. The capacity of such a drainage system as at risk of being overwhelmed with water during storms and it is consequently desirable to prevent an excessive amount of water arriving at a reservoir or tank. The arrival of a large volume of water in a short period of time can cause localised flooding.
It is known to use water attenuation tanks to store storm water, and then gradually release the water to a reservoir or other tank. These are costly to install since they are often made of concrete or steel and the delivery costs and the installation time are high. There is also the need for continual maintenance to ensure that the water is released to the reservoir or other tank at the required time. The water can be released by manual intervention, or by an automated system.
US2011/0255921 A1 discloses a storm water retention cell containing an assembly of hollow frustrum-shaped bodies arranged and supported on a horizontal support. The assemblies are arranged in alternately invert layers with the ends of the frustrum-shaped bodies interconnected to form vertical support columns within the cell which are horizontally stabilised by horizontal support structure. The aim is to collect and store storm water.
U.S. Pat. No. 6,095,718 discloses a container for receiving and storing fluids gathered and discharged from a drainage structure. The container comprises an impermeable plastic envelope around a supporting framework of at least two vertically stacked laterally extensive mats. Each mat comprises a backing grid having a plurality of intersecting struts defining grid openings therebetween; and a plurality of spaced support members projecting from said backing grid, whereby fluid may flow vertically through said backing grid and laterally between said support members. The aim is to collect and store water in the container. Such containers are often structurally unstable and relatively expensive to manufacture and install, thus limiting their practical utility.
A further solution is to provide a device containing a pipe which takes a long route through the device by undulating back and forth through the device. This device slows the movement of the water to the reservoir by increasing the distance traveled by the water to reach the reservoir or tank. It is essential that the pipe remains clear as any blockage will prevent the water from reaching the reservoir. Such a device is usually wrapped in a geo-textile material to prevent earth and sediment reaching the device. This requirement adds an additional and difficult step in the installation process.
U.S. Pat. No. 5,788,409 discloses a drain field container system which filters sewage water. The system comprises a distribution box buried beneath the ground for receiving liquid waste from a septic tank. The liquid waste flows from the distribution box via a plurality of pipes to a plurality of drain field containers. The drain field containers are constructed of a sturdy waterproof material. Each drain field container contains a filter made from gravel, crushed stone, pea stone, sand or a filter cartridge constructed using a honeycombed nylon mesh. The sides and top of the container are waterproof so that unfiltered water cannot seep out the container but must pass through the filter to exit the container. The filtered water can then percolate out of the bottom of the container into the earth or be piped into a storm drain. The purpose of the system is to filter sewage water. This document does not discuss the problems associated with handling a large volume of storm water in a short period of time.
There is a need for a storm water delay device which can be easily installed. There is a need for a device which has a reduced likelihood of becoming contaminated with earth from the ground. There is a need for a device which does not need to be controlled to release water, but that releases water without any manual or automated intervention. There is a need for a device that can hold a greater amount of water per unit volume. There is a need for a device which is environmentally acceptable and economical in terms of production, installation and use. The present invention solves these problems.